100 New experimental Researches 
The whole of the preceding research ‘is closely ‘interwoven ° 
with a question of the first importance in chemical philosophy ; 
what are the relative portions of temperature denoted by the 
graduations of our thermometric scale? Mr. Dalton regards the 
progressive elasticities of aqueous and ethereal vapour as afford- 
ing countenance, if not support, to his thermometric innovations. 
He affirms, that if our instrument for the measuring heat were 
accommodated to his doctrine, the quantity of expansion of its 
mercury is as the square of the temperature from its freezing 
point ; then ‘* the force of steam in contact with water increases 
accurately in geometrical progression to equal ‘increments of 
temperature, provided these increments are measured by a ther- 
mometer of water or mercury, the scales of which are divided by 
the above-mentioned law *.”’ 
Were this position true, it would certainly bring a powerful 
analogy in aid of his theoretical views. We are now furnished 
with data to verify, or refute it. ‘The following’ tables show the 
correspondence between that principle and experiment. In the 
table of aqueous vapour, the first column presgpts his geometri- 
cal progression of that vapour, coordinate with his equal inter- 
vals of real temperature contained in the second. In the third, 
are the coresponding points of the common scale, as‘ given by 
Mr. Dalton. To these points the elastic: forces, as determined 
by experiment, are placed opposite in the fourth column. 
Table second, for vapour of ether, is similarly arranged ; ‘the 
first three columns being Mr. Dalton’s; the fourth, the faithful 
transcript of observation. 
“« The force of the vapour of sulphuric ether,” says Mr. Dal- 
ton, “in contact with liquid ether, is a geometrical progression, 
“having a less ratio than that of water.” ‘« Ether; as manufac- 
tured in the large way, appears to bea very homogeneous |i- 
quid. I have purchased itin London, Edinburgh, Glasgow, and 
Manchester, at different times, of precisely the same quality in 
respect to its vapour t.” This shows that no exception can be 
made to my experimetuts on account of a supposed difference in 
the quality of the ether. From the mode of conducting my ex- 
periments, there-remained always a quantity of liquid ether in 
contact with the vapour, a circumstance essential to accuracy in 
this research. The results were verified by frequent repetitions, 
and discover, in my opinion, the consistency of truth. 
* New System, vol. i. p. 11. + Ib.'pp. 20, 21. 
TABLES 
